The goal of the proposed research project is to improve knowledge of sound transmission in various pathologic conditions affecting the human middle ear, and apply this information to improve postoperative hearing results after surgical procedures (tympanoplasty and mastoidectomy) for chronic otitis media. Physiologic, anatomic and audiologic data obtained from studies on temporal bones with normal, diseased, or surgically modified middle ears will be used to test and refine quantitative models of the human middle ear. Physiologic studies will consist of acoustico-mechanical measurements (middle ear input impedance, stapes footplate motion, oval and round window pressures) made on fresh temporal bones extracted from human cadavers to characterize the following clinically relevant situations: type IV tympanoplasty reconstruction; effects of mastoidectomy cavities and of fluid in the middle ear; ossicular reconstruction; and ossicular, oval, and round window fixation. These measurements will be complemented by light microscopic and audiometric studies from subjects with normal and pathologic middle ears. These physiologic, anatomic, and audiologic measurements coupled with quantitative signal processing analyses should allow us to explain signal transmission in pathologic and reconstructed ears in terms of the physical properties of the structures involved. Such knowledge can aid otologic surgeons in selecting from a variety of tympanoplasty techniques, or in modifying techniques, in order to optimize postoperative hearing results.